Reply With QuoteDid you do the reset thingy with the Nanocom after replacing the sensors?
Fossicker
Phantom rough idling issue in a straight V8 Discovery 2
Dear brain trust:
My D2a V8 has a rough idling issue which I can't seem to fix. It also throws up a lot of O2 diagnostic trouble codes. Car has around 120,000 km on it.
Confirmed:
- P0130 - O2 bank 1 circuit malfunction
- P0171 - system too lean bank 1 (passenger's side)
- P1171 -
- P1174 -
- P0150 - O2 bank 2 circuit malfunction (driver's side)
- P0174 - system too lean bank 2
Here's what I've tried in order:
- I changed spark plugs (8x NGK)
- I tried 3x different MAFs (2x brand new Bosch, 1x from a wreck)
- I changed air filter, and air filter top lid (clamp was broken)
- Mechanic changed spark plug leads (aftermarket, grey ones)
- I changed O2 sensors (2x new Bosch)
Unrelated work done:
- Mechanic: changed rocker cover gaskets (big leak before), thermostat, water pump, coolant flush, throttle body base (big coolant leak).
- Mechanic visually inspected at vacuum hoses, doesn't see any damage or cracks.
Numbers I'm getting via OBD2:
0km/h (idle, coolant 26-40C)
980-872 RPM
40-20 kg/h MAF
Bank 1: 0.45-0.54V, 7-19% trim
Bank 2: 0.37-0.75V, 2-11% trim
0km/h (idle, coolant 81-87C)
614-703 RPM
10-16 kg/h MAF
Bank 1: 0.03-0.06V, 25% trim
Bank 2: 0.01-0.06V, 0-25% trim
11km/h (87C)
1639 RPM
108 kg/h MAF
Bank 1: 0.89V 17% trim
Bank 2: 0.74V -6% trim
53km/h (87C)
1286 RPM
29 kg/h MAF
Bank 1: 0.04V 15% trim
Bank 2: 0.04V 17% trim
48km/h (87C)
1684 RPM
91 kg/h MAF
Bank 1: 0.39V 2% trim
Bank 2: 0.53V -3% trim
(Trim and MAF numbers have been rounded.)
What do you suggest that I try next?
Wizard
SubscriberDid you do the reset thingy with the Nanocom after replacing the sensors?
2002 D2 4.6L V8 Auto SLS+2" ACE CDL Truetrac(F) Nanocom(V8 only)
Fossicker
You mean clearing the error codes? Yep, I cleared them with my ODB2 reader (Vgate device, iOS app Car Scanner).Originally Posted by biggin
I don't have a Nanocom (pricey!)
ChatterBox
SupporterYou need to reset the adaptions.
RoverLord
Not compared to the parts canon.
JayTee
Nullus Anxietus
Cancer is gender blind.
2000 D2 TD5 Auto: Tins
1994 D1 300TDi Manual: Dave
1980 SIII Petrol Tray: Doris
OKApotamus #74
Nanocom, D2 TD5 only.
Wizard
SubscriberYeh, that’s what I meant.
2002 D2 4.6L V8 Auto SLS+2" ACE CDL Truetrac(F) Nanocom(V8 only)
Fossicker
Ah, gotcha. Does disconnecting the battery do this?
Can other tools do this apart from a Nanocom? A friend has a fancy Autel but he's out of town at the moment
ChatterBox
SupporterI don't know if disconnecting the battery will reset or not, other tools would work bit I don't know which ones.
The Motronic has pretty good OBD2 compliance so should be reasonably easy to sort.
Secondly, whilst I'm unable to get to a computer at the minute, I quickly did the sums in my head on your MAF readings.
You quote an RPM of 900 with a mass air reading of 40 kg/hr, that alone should set off alarm bells. A 4 litre 4 stroke engine @ 900 RPM should =
8*500mg*(RPM/2)*60
= 4000*450*60= 108 kg/hr @ 900 rpm.
The 500mg is a rough guess based on sea level and pleasant ambient temps!!
If the engine is fuelling based on 40 kg/hr, it will be running dangerously lean.
What I don't understand is that it *should*
Still be running closed loop, although maybe it's so far out of whack the adaptions are OOR, so open loop it is...??
Either way, don't run it like that, it'll be a bit hard on the valves.
*Disclaimer, I know almost nothing about the Motronic 5.2.1 engine management system and petrol engines!!
ChatterBox
SupporterUpdate to the above..
I had opportunity to test car scanner on a V8 D2 and got the same air mass reading.
I'm pretty certain that the car scanner app is misreporting g/s as kg/hr.
So 40 g/s = 144 kg/hr.
That means the issue lay elsewhere.
And that's why dedicated tools are the go.... It stops premature firing of the afore mentioned Cannon.
Fossicker
Oh, interesting! Thanks for looking into this mate!
The mechanic looked at it with his Solus Edge Snap-On (way more advanced than the Car Scanner app) and it showed the same kg/h readings. Does your Nanocom show something else?
Also, I noticed that while driving, both ECUs run in closed loop, but when stopped at a traffic light, I get ECU2 at open loop (but ECU1 stays closed loop):
O2.jpg
(Also, there's two ECUs?)
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